Conventional flexographic printing presses and methods involve six major components; ink well, ink, ink applicator called an inking roll, ink dispenser called an anilox, image plate called a photopolymer plate and print material referred to as the substrate.
The inking roll is a rubber cylinder that rotates in the ink well, which is filled with ink. By capillary action, the ink adheres to the surface of the rubber cylinder. As the inking roller continues to rotate it will encounter the anilox roller. As the two cylindrical surfaces contact each other (rolling pinch), ink is forced into the rough outer surface of the anilox, thereby filling the voids (called cells) with ink. The anilox in turn rotates to carry its ink laden surface towards a doctor blade that mechanically scrapes into the face of the anilox in a shearing-like action. This doctor blade, referred to as a leading edge doctor blade cuts into the ink at the surface of the anilox removing all ink except what remains below the anilox rough surface (in the cells). The action of the doctor blade causes wear and eventual failure of the anilox.
As the anilox continues its rotation, the cells loaded with ink approach the photopolymer plate, which is mounted on its own rotating cylinder. As the two surfaces of the anilox and plate contact each other (rolling nip), the image plate contacts the ink in the anilox's cells and, again via capillary action, lifts the ink from the cells.
The ink laden photopolymer plate continues its rotation until it contacts the substrate and transfers its ink to the substrate to make an impression (image) on the substrate corresponding to the image defined in the plate.
Persons skilled in the flexographic printing art understand that the anilox roll is a key component of the printing press. It is critical that the anilox operate in an optimum manner since it receives and dispenses ink in specific volumes to control color and quality of the printed product.
The conventional anilox roller comprises a steel cylinder with ceramic material bonded to its outside circumferential surface. The ceramic surface is also laser engraved with precise, microscopic indentations, called cells. These cells, when filled, dispense ink to the photopolymer plate. The photopolymer plates receive ink in amounts according to the volume in each cell. Different cell sizes correspond to different amounts of ink that can be transferred to the plate. Also, the ceramic material is brittle, easily damaged and its cell volume cannot be changed. Thus, each printing press typically requires a large library or inventory of anilox rollers. Establishing and maintaining such a library is very expensive. Moreover, the life expectancy of a given anilox roller is short, so many replacement rollers must be purchased, thereby adding to costs.
There are several additional printing difficulties related to the Anilox rollers discussed above, including:                1. The ink well supplying ink to the anilox cylinder is open to the air, allowing ink additives to vaporize off during a production run. This requires continuous monitoring of ink quality to prevent an ink color shift.        2. Each printing press requires a large library of individual anilox rollers, each of which have numerous cell volumes and line count combinations to complete the full library for each press. It is a steep financial hurdle to establish and maintain an anilox roller library having all possible combinations. As a result, the press operator is forced to compromise manufacturing design by using the closest anilox available in the operator's library, often with deficient results.        3. Due to the huge cost of aniloxes, it is custom to share aniloxes between presses, this complicates work scheduling when two presses may need the same anilox at the same time. The aniloxes also degrade faster because of increased use time.        4. When the printer wishes to set up a new order, each anilox from the previous order must be removed for cleaning, and/or placed in storage. The aniloxes for the new order are then selected from storage and installed in the press. This contributes to press down time. Often, on short order runs, it will take longer to set up the press with new aniloxes, than it does to print the work ordered.        5. Anilox surfaces are most often made of ceramic, and are extremely fragile. A simple bump or pressure from fingers can destroy an anilox surface. Often, damage from removal and rough use destroys the anilox before it can wear out. The more frequently an anilox is exchanged the shorter its life expectancy is.        6. Mixing ink for a press is a challenge. Chemical engineering aspects and color technology must all be correct for predictable use. Mixing ink accurately is not easy, in fact, bad ink on a press occurs at a rate exceeding 30% of the time. If the ink formula cannot be changed, the anilox volume will need to be changed by replacing it. This change over consumes valuable production time.        
There have been numerous attempts to control ink flow to account for worn anilox rollers and/or anilox rollers with less than ideal characteristics for a given print job. These attempts focus on providing volume control of the ink flow dispensed to an ink roller by controlling the opening of the supply port to the ink roller. But such attempts have been less than ideal because they do not address the necessary ink delivery (control) management, or the even distribution of the ink at the anilox roller gap point. As a result, there is a continuing need to provide for an improved ink fountain apparatus and method for distributing ink to the anilox roller.